1.20.30 fixed MCPE-159736, in which it was possible to duplicate custom blocks that were wearable, due to the click to equip behavior. However, this has resulted in several behavior packs that added mob heads to supplement the existing Skeleton/Zombie/Piglin/Dragon heads no longer being able to stack their items.

If minecraft:wearable is not appropriate, there should be a new property that can be added to items to allow them to behave similar to existing skull entities and carved pumpkins, where they can both stack and be wearable on the player's head.